RC Basics / Essentials

22/9/21

Hello friends and fellow RC enthusiasts around the world. I hope you are all well.

I should have started my blogging experiences with this post 19 months ago. I say this as I am going back to basics in this post. This in order to show you need to operate (in this case) an RC car. However, all RC vehicles (boats, planes, helicopter, spiders) require the same basic components or equipment. Another reason I am writing this is because, when frequenting another social media site I came across a chap who was new to the hobby and wanted to upgrade a classic RC with all the modern parts. However the chap did not have any previous experience or know anyone who knew about RC car's. I did send the chap some YouTube video tutorials but they didn't help. The chap didn't say as much, but I think he was embarrassed to ask any questions and IMHO also needs to know some basics of the hobby to start him on his way. So here I am, and here we go.

Transmitter

To control any RC vehicle, you will need a controller to send commands to it. This is called a transmitter. They come in all shapes, sizes and prices. Most people often think of the conventional stick type transmitters (pictured below), which are still available to this day and are still very popular in the flight models. This is possibly due to the fact of the amount of channels needed for a flight model that can be used from a stick controller.

 Handheld transmitters have seen a major overhaul in technology in the last 15 years, especially with the introduction of the 2.4GHz transmission frequency. Prior to this, the  transmitters had to use crystals of different frequencies to communicate. This meant that at race meeting, you would have a different set of crystals to the other 7 drivers, as there were only 8 bands to use in the 27MHz radio range.  The introduction of the 2.4GHz system banished the need for crystals and became the new dedicated RC frequency worldwide. The new 2.4GHz system can operate without fear of interference from other RC users, has a longer operational range and is more efficient on it's batteries. They also seem to be a lot cheaper than they did in the 1980's.

As with anything, there are some big name brands in the transmitter market that cost lot's of money. Yes, they may have a solid reputation but these days cheaper brands can also be worth an investigation. Another factor that will also command more money is the amount of channels you need to control your vehicle. For instance, a rock crawler with locking differentials and a three speed gearbox will need 4 channel system. One for the steering, one for the locking diffs, electronic speed controller and one for the gear change. I have seen articulated truck model's with a massive 16 channels that are simply amazing in every single detail. I myself only need a 2 channel system for racing, one for the steering and the other for an electronic speed controller. Happy days for me.

As the transmitter is an electrical device, it will need power. 

The cheaper controllers still use the conventional 8xAA batteries but are also available with rechargeable battery packs also. Some rechargeable packs are Li-ion and some are NiMH, both packs are good to use for a year or more. 

These types of controller also come with a dedicated charger that plugs directly into the handset. The above picture shows the charge socket indicated with the yellow arrow.

Above is a picture of a 2.4GHz, 2 channel RC transmitter. It is an Etronix brand and cost around £30 and included a receiver. This style of transmitter is called a "pistol grip" controller. The small wheel and tyre have control of the steering or the car, whilst the trigger controls the throttle amount or speed. I do love this style of controller for a car, it just feels perfect for me. 

As you can see in the above picture, the 2 channels have a fine tune system. This will be the case for all transmitters, whether software driven or analogue as in this case.

The arrows in the above picture indicate:-

White star top left = steering reverse servo.

Blue star, top right = throttle reverse servo.

Pink arrow = Bind with receiver key.

Yellow arrow = Brake & throttle adjust.

Orange arrow = Throttle trim adjust.

Green arrow = steering trim adjust.

Black star bottom middle = power on/off switch.

Although we have only 2 channels, there are many minor adjustments can be made to each transmitter. 

The operation of each dial corresponds to:-

The white star will reverse the operation of the steering. 

The blue star will reverse the operation of the throttle.

The pink arrow is used to pair the transmitter with another 2.4GHz receiver.

The yellow arrow is used to trim the brake and throttle to your desired position.

The orange arrow is used by nitro or gas trucks to achieve tick over.

The green arrow is used to trim the steering and make the car drive in a straight line.

Both reverse operation servo switches are now days rarely used as racers got used to that  racing style. Some planes, boats and gliders still prefer the reverse servo switches and so the functions stay. 

The black star switches the transmitter on or off. It is good to get into the habit of always switching on the transmitter first and then the model, always. Failure to do so can end up with the vehicle moving away under it's own power and crashing into something. I have been guilty of this mistake on occasion. It is also advised to fit a fail safe, if one isn't already fitted. The failsafe will stop the vehicle if it loses it's signal with the transmitter, which is perfect for grounded vehicles but not all RC models. I myself can only speak about RC cars and cannot comment on how other RC models overcome this potential problem. 

The range or distance of operation with the 2.4GHz system is around 250 meters, however I would not advise being that far from the model. Firstly it would be difficult to observe and you cannot see the terrain well from that distance. Again I can only comment on RC cars and buggies. 

Some more expensive 2.4GHz transmitters have memory to store the settings of 10 or more different RC cars, so if you have an RC car collection, you only need 1 transmitter for your entire fleet. I would imagine this facility would be available to all other types of RC vehicles. One controller to rule them all, as it were. 

Receiver

If you are sending a signal or commend to any device, the said device needs a receiver on the same wavelength. In the case of the 27MHz transmitters and receivers used corresponding crystals that I mentioned earlier. This is not the case with the 2.4GHz systems and each receiver can be bound to any transmitter. The transmitter itself can be bound to almost limitless receivers. 

 In the picture above we have a typical 2.4GHz, 3 channel receiver. The top yellow arrow points to a jumper pin that, inserts into the bind slot (also arrowed yellow(CH3/BIND)) and the little pointer is used to press the transmitter bind key (see transmitter pictures). When the bind process is complete a tiny LED will flash on the receiver to confirm binding was successful. Once binging is complete, remove the jumper pin and it's ready to use. This particular receiver also boasts a built in fail safe to ensure the car does not run off if the receiver loses contact with the transmitter.

The top row of the 3 pin plugs are the inputs for a battery pack, depending on your setup choice. The next row down is channel 3 and the binding slot. The next row is channel 2 and normally controls the acceleration on a car with the aid of an ESC. The bottom row are for a steering control servo.

A lot of people often connect their servo's and ESC's the wrong way around. The picture above shows how to connect everything correctly. The negative must always be on the outside as indicated above by the orange arrows. Another indicator of polarity is the small indentations to the left of the jumper pins pictured above.

This particular receiver is an Etronix 3 channel, 2.4GHz type and is very small. The receiver cost me around £10, but remember it is only 3 channel. Obviously the more channels you need, the more expensive the receiver will be. There are bigger (and more expensive) brand receivers available, but little receiver is perfect for my needs and a fraction of the cost. This receiver is approximately 60mm long, 30mm wide and 15mm high, so it is quite small. They are normally attached with sticky pads to the chassis (of a car), in a convenient position. The position of the receiver varies widely from vehicle to vehicle.  The 2.4GHz receivers are also ultra light which is great news for all RC enthusiasts.

Electronic Speed Controller (ESC)

The electronic speed controller (ESC) has been used in the RC car racing world since the 1980's. This device was designed to replace the mechanical speed controller which was widely used at the time. The mechanical speed controller was cumbersome, needed many more moving components, it was effective at the time. However, it's design was not efficient and quite an unreliable system for me. 

With the introduction of the esc, many of the components needed to use the mechanical speed controller were now obsolete. This meant the servo, speed controller, 6volts battery pack and ballast resistor could be removed saving a lot of weight in the build. The excess weight loss meant your buggy was instantly faster, more responsive and run times were greatly increased. The introduction of the esc was a game changer for many RC car enthusiasts, including myself. 

However, the esc's of that era were expensive, limited capabilities and sometimes unreliable. That is not the case in our era. They are quite inexpensive, very reliable and have many more functions. Again, as with everything we use, there is a price tag and scale; What do you want from the device?, What is the device going to powering? These are all the questions that need to be addressed before purchasing an ESC. Other questions should include; what type of motor (brushed or brushless) will be used? What type of battery do you intend to use (LiPo or NiMH)? All of the questions should be answered prior to an esc purchase. 

Above is  my Viper ECO 27 ESC. This particular ESC can run a 540 type motor of up to and including 27 Turn brushed motors. The 27 Turns refers to the windings on the rotor windings of the motor. The turns of the windings is an indication of the speed/power of said motor. Therefore the fewer the turns or windings of the rotor, the more powerful the motor will be and also increases the RPM of the motor. 

In the picture above, the black arrow points to where the battery will be connected (a Tamiya connector in this case). The pink arrow indicates the motor connections, with the blue being the negative. The green arrow point to the receiver (channel 2), with the brown being the negative. And finally the blue arrow indicated the esc on/off switch.

This esc can only be used with NiMH batteries and brushed motors only. 

In the picture above you can see the Viper ESC is programmable, but it is quite limited. And to be fair, I am not keen on that type of setup. The programming guide is also a little confusing but, the ESC has never let me down. However my next ESC (below), I will be showing has a much simpler and easier setup system that I much prefer.

The ESC above can use LiPo and NiMH  batteries, however a jumper pin needs to be moved first. The bottom yellow arrow points to the printed instructions on the esc. The top arrow shows 3 choices, firstly is forward/brake reverse. Second choice is forward and brake and lastly is forward and reverse. A really easy system to set up and I love it. This ESC cannot run brushless motors and is it's only draw back, in my limited experience. 

As you can see this ESC is a Hobby Wing, Quicrun 1060 brushed system and cost around £30. This model has a great reputation within the RC Car scene for quality, reliability and ease of setup. I have seen and read numerous articles on this particular model with great reviews and ratings. I do believe Hobby Wing did later release a brushless version of this esc.

This ESC boasts it is 100% waterproof, but I wouldn't like to find out if it is, or it isn't. The 1060 is a little bulkier than the Viper, but this ESC has a high current carrying capacity and was an expected issue when mounting the unit. Although this ESC take up a little more head room, I highly rate it. I expect the brushless version is just a good, if not a little better. All Hobby Wing ESC's come with branded decals too...mmm, I do love stickers/decals, especially when they are free!!

Servo's

Servo's look like little black boxes, almost like an ESC. At the top of the box sits a little splined cog. Attached to this cog will will a little lever or disk called a servo horn. Attached to the servo horn will be a push rod or turnbuckle. The pushrod or turnbuckle will connect to the part that needs to be moved, for example the steering of an RC car. It could also be to a carburettor of a nitro or gas engine. The servo can move all manner of things. 

  As I have stated on many occasion you get what you pay for, and you can see above is a picture of 2 Alturn servo's. They are not the most expensive nor the cheapest of brands. They cost around £16 each, yet both have different characteristics. 

Servo's come in a variety of sizes, maximum torques, maximum speeds, metal geared and so on. Some are coreless, however I have no idea what that means to be honest. 

As you can see from the picture, these servo's are fitted with a metal splined cog. Most servo's come with plastic splined cogs so these seemed the better choice to purchase at that time. There are some bigger (and a lot more expensive) names of servo's to be had, such as Savox, Futaba, Sanwa, but the Alturn servo's had almost identical operational capabilities. The servo above is a high speed servo for steering my Schumacher Cat XLS. And it is absolutely perfect for that highly demanding position.

 Above is a picture showing the different specifications for each motor, with the high speed servo on the left and the high torque servo on the right. You can also see both servo's are metal geared, metal horn gear spline/cog and ball raced for greater efficiency/longer life span. 

As I said, servo's come in all manner of sizes. Extra large, large normal, half height, small, mini and now even micro servo's. Again, all these servo's have different internals and prices. It is always a good idea to investigate what is available and what you need for the application. High speed, high torque or maybe both?  

Motors

DC motors has always been a huge and very scientific subject that keeps growing due to technical advancements on a daily basis it seems. In this section I am only going to be mentioning the 540 size motor both brushed and brushless. I can only offer a small amount of knowledge on brushless motors as I have not really had much experience with them. What limited knowledge I do know is, they are much more powerful than a conventional brushed motor. They are also was more efficient, don't wear out carbon brushes and should have a much prolonged lifespan than a conventional brushed motor.  They also need a specialized brushless ESC, but these systems are getting less expensive all the time. They also require a high drain battery (LiPo) to run with, due to the massive current capacity they require. There are also 2 types of brushless systems on the market, sensor or sensor less, and that is the end of my brushless system knowledge. 

Above is a picture of a HobbyWing brushless motor. It is an EZRUN 3652 and costs around £40. The first thing you will notice is the 3 wires coming out of it, whereas a brushed motor only has 2 wires. This is because you cannot simply reverse the positive and negative to reverse a brushless motor. The magnetic field inside the motor is reversed instead from the ESC to produce a reverse rotation of the rotor. With a brushed motor, reversing the polarity will result in reverse rotation of the rotor. 

  

Another picture of the brushless motor shows the internal components of the assembly. The motor is also pre equipped with ball bearings for prolonged run times. Impressive stuff and well built in my humble opinion. 

Above shows a picture of the brushless motor's temperature cut off switch. I had read and watched video's about brushless motors running hot, but I have to say, I do love this system judging from the evidence I have read. BTW, I am in no way connected or sponsored by HobbyWing. I wish I was. I also don't own or have any experience with the EZRUN 3652.

  Above is a picture of a conventional 540 type brushed motor. The yellow arrow above is pointing to the springs that retain the brush in place. The brushed motor has 2 of these springs and 2 brushes or bushes. 

In the picture above, I have removed 1 of the bushes from the assembly. These bushes are brand new as you can tell, but damages one's may have pieces missing and will need to be changed. Notice the 16AWG (American Wire Gauge), heavy current silicone cable needed to supply the high current, essential for most RC motors. 

The brushed motor we are looking at is my Etronix 27 turn, sport tuned motor. Although it says tuned, it is quite a timid (slowish) motor. It cost me around £18 and has ball bearings. With this motor being brushed, it can be taken apart, cleaned, serviced and rebuilt with new parts. These motors back in the 1980's were a dream as the "silver can" (standard 540 type) would break down after a period of time and were not re-buildable. This meant when the motor was broken, it was highly unlikely it could be fixed and went in the rubbish. They were normally in the kit from suppliers like Tamiya, Marui or Kyosho. The silver can is a good motor but suffered with brass or plastic bushing's instead of bearing's that drastically reduced the cars run time and overall performance. Although the 27 turn may be quite a slow motor, it is 10 times the motor "any silver can" will be. 

All motors need to engage with their drives. In the case of an RC car, we use a pinion gear. The pink arrow above shows how the pinion gear is fastened to the motor shaft. This is normally done with a set or grub screw. Pinions come with a different number of teeth depending upon the vehicles intention. The pinion on the above motor shaft is a racing cog for my Kyosho Optima and intended for racing and has a low tooth count. A rock crawler for instance may need many more teeth to deliver the torque to the wheels at a low speed. If you are a cyclist, you can imagine, it is exactly the same principal and system.

Batteries

I am currently writing an article/blog/post solely on batteries HERE and HERE. There is a lot more information on those posts than I can post here and it would only be a reiteration of what I have previously written or stated.

Wiring it correctly

There are many types of systems on the market at the moment. Some may have a different layout but, 99% of the time, this is the correct wiring of a brushed electronic RC car system using an ESC. In a previous picture, I showed you the connections for my ESC fitted with a Tamiya connection. That layout is again, 99% correct.

The picture above allows you to visualise what I was trying to portray. It is quite an easy wiring diagram and can (for an RC Car) be used for reference purposes for a brushed system. Remember never to exceed the ESC's maximum with a too powerful motor as the ESC will be damaged beyond repair. This because nearly all ESC are sealed in a waterproof/airproof, isolating, solidifying resin compound. Breaking through the hardened resin, to repair damaged components is mission impossible. Honest. Every motor and ESC are rated, so please match them together or lower turns than the ESC's max. Failure to do so can result in fire and severe injury.  

And with my little warning, I can now kindly leave you with a little more information than you had. I hope I have shown you most of the basic information that I am aware of. If not, please ask/leave a question in the comments below and I will answer them to the best of my knowledge. I am constantly learning new things and I will always share my knowledge and keep you up to date.

Until my next post, take care and keep RC'ing!

CATXLS.COM

25/9/21

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